1. Field of the Invention
The present invention relates to a film formation method and apparatus for forming a silicon nitride film (SiN film) on a target object, such as a semiconductor wafer, and particularly relates to a semiconductor process technique. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target object, such as a semiconductor wafer or a glass substrate used for an FPD (Flat Panel Display), e.g., an LCD (Liquid Crystal Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target object.
2. Description of the Related Art
In the manufacturing sequence of semiconductor devices, there is used a film formation process for forming a silicon nitride film (SiN film) as an insulating film on a semiconductor wafer, such as a silicon wafer. In such SiN film formation processes, a vertical heat processing apparatus of the batch type is often used to perform film formation by chemical vapor deposition (CVD) on a plurality of semiconductor wafers together at a time.
In recent years, owing to the demands for increased miniaturization and integration of semiconductor devices, it has been required to form an SiN film of higher quality by use of a film formation temperature lower than that of conventional CVD. As a technique for fulfilling the demands in vertical heat processing apparatuses of the batch type, there has been proposed a technique for forming an SiN film by ALD (atomic layer deposition) that alternately supplies an Si source gas and a nitriding gas to repeat lamination of films of an atomic layer level or molecular layer level (for example, Jpn. Pat. Appln. KOKAI Publication No. 2006-49809). For example, dichlorosilane (DCS: SiH2Cl2), which has a high adsorbent property, is used as the Si source, and ammonia (NH3) is used as the nitriding gas.